private async Task Init(byte[] passwordInUTF8,ICanSHA256Hash hasher)
{
var hashedBuffer = hasher.Hash(passwordInUTF8);
keyData = hashedBuffer;
}
/// <summary>
/// Construct a new cryptographically secure random stream object.
/// </summary>
/// <param name="genAlgorithm">Algorithm to use.</param>
/// <param name="pbKey">Initialization key. Must not be <c>null</c> and
/// must contain at least 1 byte.</param>
/// <exception cref="System.ArgumentNullException">Thrown if the
/// <paramref name="pbKey" /> parameter is <c>null</c>.</exception>
/// <exception cref="System.ArgumentException">Thrown if the
/// <paramref name="pbKey" /> parameter contains no bytes or the
/// algorithm is unknown.</exception>
public CryptoRandomStream(CrsAlgorithm genAlgorithm, byte[] pbKey, ICanSHA256Hash hasher)
{
_hasher = hasher;
m_crsAlgorithm = genAlgorithm;
uint uKeyLen = (uint)pbKey.Length;
if (genAlgorithm == CrsAlgorithm.ArcFourVariant)
{
// Fill the state linearly
m_pbState = new byte[256];
for (uint w = 0; w < 256; ++w) m_pbState[w] = (byte)w;
unchecked
{
byte j = 0, t;
uint inxKey = 0;
for (uint w = 0; w < 256; ++w) // Key setup
{
j += (byte)(m_pbState[w] + pbKey[inxKey]);
t = m_pbState[0]; // Swap entries
m_pbState[0] = m_pbState[j];
m_pbState[j] = t;
++inxKey;
if (inxKey >= uKeyLen) inxKey = 0;
}
}
GetRandomBytes(512); // Increases security, see cryptanalysis
}
else if (genAlgorithm == CrsAlgorithm.Salsa20)
{
byte[] pbKey32 = _hasher.Hash(pbKey);
byte[] pbIV = new byte[]{ 0xE8, 0x30, 0x09, 0x4B,
0x97, 0x20, 0x5D, 0x2A }; // Unique constant
m_salsa20 = new Salsa20Cipher(pbKey32, pbIV);
}
else // Unknown algorithm
{
throw new UnknownAlgorithmException();
}
}
